Enzyme-Sensitive Dendrimers

Raghupathi, K. R., Azagarsamy, M. A. and Thayumanavan, S. (2011). Guest-release control in enzyme-sensitive, amphiphilic-dendrimer-based nanoparticles through photochemical crosslinking. Chemistry-a European Journal, 17, 11752-11760. 

Zhang, C., Pan, D., Luo, K., Li, N., Guo, C., Zheng, X., Gu, Z. Dendrimer-doxoruhicin conjugate as enzyme-sensitive and polymeric nanoscale drug delivery vehicle for ovarian cancer therapy. Polym. Chem. (2014). doi 10.1039/C4PY00601A... 

A similar type of biotin-dendritic multimer also was used to boost sensitivity in DNA microarray detection by 100-fold over that obtainable using traditional avidin-biotin reagent systems (Stears, 2000 Striebel et al., 2004). With this system, a polyvalent biotin dendrimer is able to bind many labeled avidin or streptavidin molecules, which may carry enzymes or fluorescent probes for assay detection. In addition, if the biotinylated dendrimer and the streptavidin detection agent is added at the same time, then at the site of a captured analyte, the biotin-dendrimer conjugates can form huge multi-dendrimer complexes wherein avidin or streptavidin detection reagents bridge between more than one dendrimer. Thus, the use of multivalent biotin-dendrimers can become universal enhancers of DNA hybridization assays or immunoassay procedures. 

The general method utilized to prepare E5-Ab solutions obviates the need for stocking large numbers of reagents which would be necessary if different activation methods were used for each antibody. A number of specific antibodies immobilized by this process have shown response similar to that of the same antibodies when adsorbed as immune complexes in the Stratus system. In addition, the dendrimer-coupled antibodies have shown dramatic improvements in sensitivity, flexibility and precision for the enzyme immunoassay system. Feasibility demonstration of an assay for DNA probes is a prelude to what can possibly be achieved with these dendrimer-based reagents. 

Table I provides a comparison of the performance of the dendrimer-based electrochemical glucose biosensors. It is found that many of the dendrimer electrode assemblies show reasonable linear range and detection limit. Their stability assessment and high sensitivity values indicate good scope for commercialization. The bi-enzyme model is better than the conventional mono-enzyme model in terms of lower detection potential which can help to circumvent the interferences due to other biomolecules during the measurements.

No. Enzyme(s) /electrode Dendrimer or its composite Immobilization method Detection Technique Electrolyte Analytical Characteristics Sensitivity Ref. 

In summary, the Ion Evaporation Model is experimentally well supported for small ions of the kind that one encounters in inorganic and organic chemistry. However, when the ions become very large, such as polymers, dendrimers or biological supramolecular complexes like proteins and enzymes, the Charged Residue Model (CRM) becomes much more plausible, see Section 1.2.10. Because many applications of ESMS in analytical organometallic and physical organic chemistry involve small ions it is desirable to consider the expected relative sensitivities for these analytes when detected with ESMS. 

The kinetically controlled stereoselection depends on very small increments of free activation enthalpy. It is therefore an excellent sensitive probe for dendrimer effects. As monodispersed macromolecules, chiral dendrimer catalysts provide ideal model systems for less regularly structured but commercially more viable supports such as hyperbranched polymers. However, the results obtained by a considerable number of research groups in the field have also established that the structural characteristics of the established dendrimer systems, such as the absence of a well-defined secondary structure, have limited the development of efficient abiotic enzyme mimics based on dendrimers. To achieve this ambitious goal, more effort in dendrimer synthesis will be necessary. The use of dendritic... 

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